My boss at work who has been working on motorcycles and riding them for more than 20 years taught me how to clean out a gastank on a motorcycle that has been sitting and gotten rusty/gunky inside

1. Dump out all gas/funk from tank2. 1/2 jar of naval jelly dissolved in 2 liter bottle of water3. Dump in tank (fill completely with plain water) and let sit 24hrs4. Dump naval jelly and rinse w/ fresh water5. 1/2 cup baking soda dissolved in 2 liter bottle of water6. Dump in tank (fill completely with plain water) and let sit 2 hrs7. Dump baking soda and rinse 2x w/ fresh water8. Shake all or as much water from tank as possible9. Use 1/2 can or more wd-40 on tank to help emulsify water so rust wont start again

I used steel wool and elbow grease on mine. Then a vacuum to get most of the residue out followed by rinsing with gasoline which was filtered using a coffee filter and run through again until it came out clean.

I think that the Naval Jelly is basically phosphoric acid in a gel form. By adding water you are just turning it back to a liquid. You can find phosphoric acid already in liquid form in the bathroom cleaner section of your local store.

I have cleaned some really dirty tanks and I have cleaned them by putting various things like nuts and bolts or pennies in the tank and shake the tank and rinse with water to loosen and flush out the dirt and rust until the water comes out clean.

I have used chemical cleaners like Lime-away or diluted hydrochloric acid after the above treatment to remove the remaining rust down to shinny metal. I have never left it overnight because I didn’t want to remove too much metal and it usually doesn’t take that long.

I usually spray the inside with WD-40 and then flush with gasoline and I’m done.

A pink phosphoric acid based gel for safe and easy removal of rust from iron and steel. Naval Jelly is useful for preparing metal surfaces for painting. Paint will adhere better to iron and steel surfaces when cleaned will Naval Jelly. It is also an ideal pre-treatment for all galvanized surfaces prior to painting.

For general cleaning of iron and steel, apply full strength with a paint brush, roller or sponge. Allow a dwell time of 5 to 20 minutes depending on the amount of rust to be removed. If heavy encrustations are present, use a wire brush to clean before applying. In severe conditions, it may be necessary to apply Naval Jelly several times. If this occurs, allow a longer dwell time, overnight if possible.

The product is 100% soluble in water. Can be neutralized with a baking soda paste.

There are two main reasons for using phosphoric acid for rust removal: It dissolves rust at a much faster rate than it dissolves iron, and it leaves a nice iron phosphate coating on the clean metal surface. The reactions are: (a "_" before a number means to subscript the number.)

(1) Fe_2O_3 + 2 H_3PO_4 -----> 2 FePO_4 + 3 H_2O fast

(2) Fe + H_3PO_4 -----> FePO_4 + H_2 (gas) slow

In reaction 1, the rust (Fe2O3) gets turned into iron phosphate and water; this mostly gets washed away when you rinse the part. The phosphate part of phosphoric acid is responsible for this reaction. Reaction 2 is the reason you may see some bubbles. The iron itself is actually dissolving, but this is a relatively slow reaction. The H+ ions from the phosphoric acid are responsible for this reaction. You're not going to lose any worthwhile amount of metal to this reaction, but this is also the reason you don't leave the acid on the part for more than about 15 minutes. The layer of FePO4 that is left on the surface adheres strongly enough due to surface effects that it does not wash away with the rinse, hence the good protection from further rusting. (Note: reaction 1 is a simple exchange, 2 is oxidation-reduction; i.e. Fe+++ ---> Fe+++ and Fe(0) --> Fe+++.)

So I guess diluting it in 2 litres of water then filing tank would make it remove metal at an even slower rate...however if the tank has rust completely thru, it might eat a hole in the tank (which means its time for a new tank anyway)

Hey guys, just tried a new method I found earlier this week. I Have a 82 650 honda nighthawk, had a badly rusted tank. And is now pretty clean . The process is simple, it's electrolysis . Remove fuel valve from tank, and plug off the hole. Fill tank with water , then add 1 tablespoon of arm and hammer WASHING soda per gallon of water in the tank. Put cap on, and shake well. Remove cap, make simple cap for process. I used plastic with a hole large enough for the metal treaded rod i stuck in the hole. The idea is to fashion a cap that sits in place with a metal rod that goes deep into the tank but does NOT touch the tank anywhere along the way. bare a section of metal near the seat end of tank where most have mounting hole. Get out your battery charger, hook positive lead to rod in cap, hook negative lead to bared section near mount hole. turn on charger and leave. Check 2 times a day for build up on positive "rod", and then turn on again, i went 2 days ...rinsed out well, sprayed with w-40 to help dry it out. It's back on the bike, and almost ready to ride

Hey guys, just tried a new method I found earlier this week. I Have a 82 650 honda nighthawk, had a badly rusted tank. And is now pretty clean . The process is simple, it's electrolysis . Remove fuel valve from tank, and plug off the hole. Fill tank with water , then add 1 tablespoon of arm and hammer WASHING soda per gallon of water in the tank. Put cap on, and shake well. Remove cap, make simple cap for process. I used plastic with a hole large enough for the metal treaded rod i stuck in the hole. The idea is to fashion a cap that sits in place with a metal rod that goes deep into the tank but does NOT touch the tank anywhere along the way. bare a section of metal near the seat end of tank where most have mounting hole. Get out your battery charger, hook positive lead to rod in cap, hook negative lead to bared section near mount hole. turn on charger and leave. Check 2 times a day for build up on positive "rod", and then turn on again, i went 2 days ...rinsed out well, sprayed with w-40 to help dry it out. It's back on the bike, and almost ready to ride

What kind of metal rods?

Is this some sort of electroplating or does it anodize the inside of the tank or what..seems pretty interesting, but what does it do exactly?

Yes it is a form of electrolysis ,the process is called reverse electro-plating. The rode in the tank is steel (or most that are rustable, DO NOT use stainless as it produces nasty gases). Electricity flows from positive to negative with DC power. With positive hooked to the rod, and negative to the tank, the current flows from the tank to the rod. When the current passes through the rust on the inside of the tank, bits break off and follow the "current" flow through the electrolyte solution to the positive rod. When the current passes into the rod, the rust particles slam into it, but are not able to follow...so they build up on the rod. You wind up with a nasty looking solution in the tank as i becomes saturated with rust, and have to clean the rod a couple times a day...but when you drain the solution, and rinse...it is clear that the process works good

not magnetic, electrolysis. particles of one metal flow from negative of voltage source to positive source. the flow is created from the constant stream of electrons passing between the + and _ of the dc voltage supply (the charger)

The rust is dissimilar. That's really cool stuff. shifting nature into reverse and having it do your bidding. I can't wait to try. sounds a bit dangerous? I probably shoud not... I have a method that works great on really ugly junk yardtanks. It's easy but may not be a first choice due to the possibility of damage although I've not suffered any: Remove petcock(s) apply duct tape, open gas cap, spray WD40 for 5 seconds, throw in a hand full of lock washers (count them), close cap, wrap tank in the blanket you use for a creeper, tape it up and throw it in the dryer (no heat setting!) 3 hours will make it shine. remove every washer you counted. If you have a purdy bike that you had to make payments on then I'm not advising it but with small 3/8 washers and a thick blanket, there should be no problem. Done it several times. Watch out for moms and wives. they don't understand.

I've read about a method sort of like travismhood's where you get a couple of handfuls of lead shot, toss it in the tank, seal it up, then cushion the tank well inside a sealed 5 gallon bucket.Take it over to the paint department at Home Depot and have them put it in the 5 gallon shaker.Supposedly cleans 'em up really well..

My only concern is can/will it damage the tank if the rust is close to eating thru?

I'd think that you'd want it to punch through, if it's that rusty.Way better than having the tank give up 4 or 5 gallons while you're tooling down the slab, once the rust finally makes it through. Not a fun shower. Better to find out when it's dry.That way, you can decide whether to repair it or junk it.